Probiotic bacteria are used to balance a disturbed intestinal microflora and related dysfunctions of the gastrointestinal tract (GIT). They could be an effective alternative to the use of synthetic substances in nutrition and medicine. This study has investigated the effect of probiotics, prebiotics and potentiated probiotics on the health and production of broiler chickens, ROSS 308 hybrid, 1-42-days-old. The chickens were divided into six groups, 30 chickens in each. Group K served as a control, chickens from group L were supplied probiotics, those from groups O and E received prebiotics, and the diet of chickens from groups L+O and L+E was supplemented with potentiated probiotics. Weight gain, health of the chickens and selected biochemical and hematological blood parameters were observed. This experiment has found that the application of probiotics and prebiotics significantly improved the weight gain of broiler chickens and also affected some biochemical parameters. The study has recorded a significant decrease in concentration of serum cholesterol, as well as the activity of alanine aminotransferase. The individual groups of chickens differed in the content of total lipids, proteins, calcium, phosphorus and the activity of alkaline phosphatase. Results of our experiment indicate that supplementation of the broiler chicken diets with potentiated probiotics has a positive effect on weight gain and the health of chickens.